Here in the U.S., we don't have rules that require ISPs to retain such data, yet many ISPs (especially the largest ones) happily do so for months or years.
One of the first things I did shortly after going to work for an ISP was to create a formal retention policy. We certainly don't "record" user traffic (with the exception of a tcpdump if I'm troubleshooting, for example) anyways, but nearly nothing is kept for more than seven days. I wish more ISPs operated this way.
I know of other ISPs that do the same. It's interesting because prior to the DMCA it was all about getting more log space to help with diagnostics and troubleshooting, or running interesting stats. Now that it's fairly common for requests of dubious legal quality to be made for user information, it's really the jobs of any reputable ISP to protect their customers by limiting retention of this information.
And this ironically one of the reasons why the EU data retention directive came about in the first place: privacy laws would make retaining that data illegal.
This particular Swedish ISP is not being a rebel, they're doing what they would be legally obliged to do.
One of the first things I did shortly after going to work for an ISP was to create a formal retention policy. We certainly don't "record" user traffic (with the exception of a tcpdump if I'm troubleshooting, for example) anyways, but nearly nothing is kept for more than seven days. I wish more ISPs operated this way.